Using element groups to define multiple types for the same element

The schema below validates ok with XMLSpy, and allows the "subelement" to
have variable
content (string/date/number).

<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2000/10/XMLSchema" targetNamespace
="test" xmlns="test">
  <xsd:group name="group1">
    <xsd:sequence>
      <xsd:element name="subelement" type="xsd:string"/>
    </xsd:sequence>
  </xsd:group>
  <xsd:group name="group2">
    <xsd:sequence>
      <xsd:element name="subelement" type="xsd:number"/>
    </xsd:sequence>
  </xsd:group>
  <xsd:group name="group3">
    <xsd:sequence>
      <xsd:element name="subelement" type="xsd:date"/>
    </xsd:sequence>
  </xsd:group>
  <xsd:element name="test">
    <xsd:complexType>
      <xsd:choice>
        <xsd:group ref="group1"/>
        <xsd:group ref="group2"/>
        <xsd:group ref="group3"/>
      </xsd:choice>
    </xsd:complexType>
  </xsd:element>
</xsd:schema>


Is this a valid schema? Will it validate all the following instances ok
(ignoring namespace stuff)?

<test>
  <subelement>abc</subelement>
</test>

OR

<test>
  <subelement>2001-05-18</subelement>
</test>

OR

<test>
  <subelement>125</subelement>
</test>


If so, does a group definition provide some type of "local" scoping of the
subelement content model such that the above doesn't cause conflicts?

It just didn't look/feel right to me.

Thanks
Michael